SubscribeFuelled by the surge in global population and by rising per capita fiber consumption, world fiber consumption has continued to grow. While in 2002 demand was 63 million tons, it is expected to reach 80 million tons by 2010.
Man-made fibers (e.g. polyester, polyamide, acrylics, cellulosics, polypropylene) share about 60 % of the global consumption. For several years now, a big potential for PP has been detected in the carpet industry and the nonwovens business.
Nowadays, polypropylene is also becoming increasingly important in the form of textile yarns used for apparel and in automotive applications. Textile yarns made of PP are used in:
- Sportswear
- Upholstery
- Underwear
- Outdoor furniture
- Leisure wear
- Components for luggage
- Hosiery
- Medical textiles
- Socks
- Automotive
Well-known producers of garments in Europe are, for instance, Helly Hansen with its LIFA® trademark, also called dry fiber technology, Löffler in Austria with its Transtex® and X-light® trademarks, and JBS with its FUNCTION® products. Such fabrics are made out of 100% PP (see fig. 1) and blends with cotton or wool, arranged in a two-layer system (see fig. 2).
Professional athletes swear by their functions, and increasing numbers of people become demanding consumers requiring high-quality equipment for their leisure activities. They are willing to purchase high-priced products offering an exceptional functionality. Recently, Austrian law-enforcement agencies were outfitted with two-layer Polo shirts including PP yarns, and the Italian government has ordered nightwear made of 100% PP for its police force.
Function:
The PP fiber is the first fiber that is in contact with the skin, does not absorb moisture, and therefore keeps the skin dry. PP spun yarns and filaments are popular, with worldwide interest now zeroing in on filament yarns. The enhanced quality of filaments, better knitting and weaving performance coupled with fewer yarn breaks and the total absences of pilling are the benefits.
In recent times, increasing attention has been paid to the recycling of used products. A great need for action has been detected in the automotive industry, since the EU Directive 2000/53 EC on end-of-life vehicles will in the future require that up to 95 % by weight be reusable. It is up to the industry which parts will be reused, but, depending on the size and type of a car, it includes about 25 kg of textiles or more.
Highest requirements in terms of abrasion resistance, UV and color fastness, and others must be fulfilled. Very good results are achieved by combining air and friction textured yarns in woven fabrics for seats. Progress in development is made in cooperation with the European automotive industry. Consequently, in the near future, parts such as door panels for SEAT and FIAT will be made of PP. As several parts such as carpets, floor mats, and rear shelves are already made of PP, PP could even become the material (fig. 5). The most important arguments in favor of its application are these:
- It is recyclable/eco-friendly
- Has the lowest specific weight (see fig. 4)
- Permits easy cleaning
Further important properties are:
- Chemically inert, hydrophobic/lowest
- Moisture absorption (see fig.3), good
- U V stability, colorfast
Important improvements were accomplished with the raw material (Metallocene), masterbatches, additives, and types of spin finish. Based on these developments and improvements of the spinning process, it has become possible to produce high-quality yarns and extra-fine yarns including microfilaments (single titer about 1 dpf). Fine dpf textured yarns give comfort and softness to knitted or woven fabrics.
Together with Ind. Murtra, Spain, and RPR, Italy, we have improved the spinning and texturing process and are capable of producing top-quality yarns. At SML, spinning and texturing trials on pilot lines have been conducted in order to evaluate the yarn. Furthermore, we have used our yarns to create fabrics and make garment items such as socks and shirts.
Yarn specification:
PP POY yarn titer: 78 – 333 dtex
range of single titer: dpf 1–6
tenacity (Met): POY 2 - 3 g/dtex
textured yarn about 3.5 g/dtex
e.g., POY (Met): ---- 116-dtex f74
tenacity: ----- 2,6 g/dtex
elongation: ----- 136 %
uniformity: ----- Uster 0,83
Depending on the required touch and application, POY yarns can be friction or air textured. With friction texturing, the yarn is stretched and twisted between the friction discs (false twist). Such yarns have a high bulk and impart a soft touch to the fabric. It is typically used for knitted articles.
In the air texturing process, two or more threads running at different speeds (overfeed) are put together and moved through an air jet. In the air stream, the yarn forms loops and assumes a hairy character – similar to that of natural fibers. It is frequently used in woven articles that get a rough (harsh) touch. As PP is spun dyed, one does not need a dyeing department for this fiber material. In general, fabrics are washed, dried, and fixed on a stenter frame in low temperatures of 125°C max.
Ing. Günter Klambauer
Product Manager Filament Extrusion